Polarised microscopy is a technique that uses polarised light to enhance the contrast of specimens, allowing for the identification of structures and materials that are otherwise difficult to visualise. This method is particularly important in clinical practice for diagnosing conditions such as gout and certain types of crystalline arthropathies, where birefringent crystals can be observed. A key association is the detection of monosodium urate crystals in synovial fluid, which confirms gout.